Lockheed C-121 Constellation

C-121/R7O/R7V Constellation
A Military Air Transport Service C-121G Super Constellation flying near the Golden Gate Bridge.
Role	Military transport
National origin	United States
Manufacturer	Lockheed
Designer	Clarence "Kelly" Johnson
First flight	March 14, 1947
Introduction	November 12, 1948
Status	Retired, two flying in airshows
Primary user	United States Air Force United States Navy
Produced	1947 to 1958
Number built	332
Developed from	L-749 Constellation L-1049 Super Constellation
Variants	R7V-2/YC-121F Constellation EC-121 Warning Star

The Lockheed C-121 Constellation was a military transport version of the Lockheed Constellation. A total of 332 aircraft were constructed for both the United States Air Force and United States Navy for various purposes. Numerous AWACS versions were also constructed. The C-121 later saw service with smaller civilian operators until 1993.

Lockheed's first attempt at a military version of the Constellation airliner had been unsuccessful. This was largely due to the problems encountered by the Wright R-3350 engines that powered the aircraft. After the war, the few military Constellations built (designated C-69) were retrofitted by Lockheed for use in the post-war airline industry as the L-049.

In 1947, Lockheed unveiled a more economical Constellation. The L-749 as it was known, had extra fuel capacity and a more economical version of the R-3350. However, Lockheed had lost 1200 workers that same year. By 1948, production of the L-749 was at a near halt. It was then that the United States Air Force (USAF) signed a contract with Lockheed for ten L-749A aircraft designated the C-121A. The United States Navy (USN) had also placed an order for two AWACS versions of the L-749A designated the PO-1W (later WV-1). The first L-749A variants off the production line were for the US military.

The C-121A versions differed from the L-749 only through having a reinforced floor to handle cargo, and a large aft loading door. Although originally intended for cargo transport duties, they were usually fitted out with 44-seat passenger transport interiors. The aircraft also consisted of a five-man crew with four relief crew members on standby. All C-121As were assigned to the Atlantic division of the Military Air Transport Service (MATS). The aircraft would later see service in the Berlin Airlift. Dwight Eisenhower and General Douglas MacArthur both used the C-121A as their personal VIP transports. In 1950, six of the C-121A Constellations were modified as VIP transports and redesignated VC-121A. The last C-121As were retired in 1968.

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